Are you using a regular, wired, landline phone, or a wirelss/cell phone?Landline phones ring signals are driven by a voltage pulse. You can detect that pulse with an appropriate Zener diode, and tie that detection to a blinking circuit.Cell phones do not typically have a standard signal that tells you someone's calling, although you could maybe get that information out of the Bluetooth interface if it's supported. (This is approximately 100,000 times more complicated than the landline version!)

Depending on the phone you have, you could connect a wire to the phone's speaker or vibrating motor and use it as a signal to activate your circuit.

There are a dozen ways you can do this. Depends on the features and level of complexity you are aiming for.

(note: this is how terrorists use cell phones to trigger bombs )

im trying to make a iPhone case with led in it, and active when calls receives.and i want to apply the concept of mobile calling blink accessories which the accessory attach to the phone and blinks when someone calls.ex (

As far as I know, mobile call sensors just sense significant radio power nearby in the general cell phone spectrum. They don't even distinguish the particular carrier frequency. The reason this works is that power falls off as one over r squared, so there'll be close to a watt available close to the phone, even thugh there are only milli- or micro-watts available at the cell phone tower. Also, cell phones just a few feet away will be relatively significantly weaker.

As far as I know, mobile call sensors just sense significant radio power nearby in the general cell phone spectrum. They don't even distinguish the particular carrier frequency. The reason this works is that power falls off as one over r squared, so there'll be close to a watt available close to the phone, even thugh there are only milli- or micro-watts available at the cell phone tower. Also, cell phones just a few feet away will be relatively significantly weaker.